One of the previously-used conventional vehicle seats provided with a child seat by using the rear side of a seat back is illustrated in FIG. 8 and is disclosed, for example, in Japanese patent laid-open publication No. 131335/1985.
According to the aforementioned conventional vehicle seat, a child seat is constituted in a manner such that a stay(not illustrated) of the combination of a seat cushion and head rest for a child (207) is caused to engage an engaging hole(not illustrated) perforated at a lower portion of a seat back (201) under a condition that the seat back is shifted frontwardly (arrow F) as illustrated in FIG. 8 against a seat cushion (203). Arrow (R) denotes the rearward direction in FIG. 8 and reference numeral (205) denotes a movable supporting mechanism in that figure.
Furthermore, each end of seat belts (209,209) is fixed to the seat cushion (207) and also to the rear side of the seat back(201).
It may be noted, however, that since the aforementioned seat belt (209) is merely coupled to the seat back (201) and the seat cushion (207) at two points therebetween, the problem is encountered of eventually having to make the cushion (207) larged-sized to enhance the rigidity thereof, resulting in increase of weight when it is desired to ensure bearing strength of the seat belt (209) satisfactorily.